No as if you can see the table from the test code then the extension loaded.
See issue 223 about game onContext game inaccurate on game change · Issue #233 · twitchdev/issues · GitHub
Never used the react boilerplate, my example code is pure javascript, nothing gets in the way like react may.
The video source makes no difference
I just went and tested my example code. Looks like Twitch broke something 
Left 3 months ago. Right. same code, right now
I have observed if there is any other extension active in the video slot then it works